Electric-clock system.



H. E. WARREN. ELECTRiC CLOCK SYSTEM.

APPLICATION FILED AUG.2|| I9I6.

2 SHEETS-SHEET I 1,283,431. Patented Oct. 29,191

lavmfor M g. Wan/M H. E. WARREN.

ELECTRIC CLOCK SYSTEM.

APPLICATION FILED AUG-2!. I916.

Patented Oct. 29, 1918.

2 SHEETS-SHEET 2.

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#MW M .UNITED STATES PATENT omen.

HENRY E. WARREN, OF ASHIiAND, MASSAOHUSETTS, ASSIGNOR TO WARREN CLOCKCOMPANY, OF ASHLAND, MASSACHUSETTS, A CORPORATION OF MAINE.

' ELECTRIC-CLOCK sYsTEM.

Specification of Letters Patent. Patented O h-29 1918.

Applicationfiled August 21, 1916. Serial No. 115,955.

To all whom it may concern:

Be it known that I, HENRY E. WARREN, a citizen of the United States, anda resident of Ashland, in the county of Middlesex and State ofMassachusetts, have invented an Improvement in Electric-Clock Systems,of which the following description, in connection with the accompanyingdrawings, is a specification, like characters on the drawingsrepresenting like parts.

This invention relates toa novel means, whereby time indications may bedistributed by means of an alternating current system.

The invention is especially applicable for use with existing commercialalternating current systems, whereby the individual users of the currentsupplied by said systems for lighting, power or other purposes, may alsobe provided with clocks which are operated by the same current and whichindicate the correct time and which are simultaneously regulated from astation of the alternating current system.

To this end I employ a synchronously driven clock, preferably having amotor provided with a rotary magnetic field, which is maintained by thealternating current, and which field is magnetically coupled to the timemovement of the clock, and I adjust the frequency of the alternations ofthe said current, so as to compensate for a difference in time betweensaid clock and means for indicating standard time.

The motor referred to may and preferably will be of novel constructionas will be described.

The means for indicating standard time may be a standard clock locatedin a station of the alternating current system, and I prefer to locatein said station a duplicate of the electrically driven clocks includedin the system outside of the said station, which duplicate clock may bedesignated a comparison clock.

The electrically driven clocks referred to are constructed to be drivenat a rate proportionate to the frequency or alternations of the current,so that, if the frequency of the current is correct or of apredetermined number per minute, the clocks in the system will keepaccurate time.

If the frequency of the alternating current should vary, then the clocksbecome inaccurate, and the frequency or alternations of the currentemployed to drive the clocks is adjusted or varied to correct theinaccuracy, which may be accomplished by adjusting the speed of theprime mover or movers in the station, so as to gradually wipe out anyexcess or deficiency in the sum of the alternations, which has causedthe electrically driven clocks to gain or lose slightly with relation tothe standard clock.

The speed of the prime mover may be varied by means of speedcontrollers, such as now commonly provided for the governors of largeengines or turbines, and this adjustment may be effected manually orautomatically.

These and other features of this invention will be pointed out in theclaims at the end of this specification.

Figure l is a diagrammatic view of a sufficient portion of analternating current system capable of distributing time indications inaccordance with this invention to enable the latter to be understood.

Fig. 2, a plan view of a clock of novel construction, which is employedin the alternating current system.

Fig. 3, a front elevation with parts broken away of the clock shown inFig. 2.

Fig. 4, a side elevation with parts in section of the clock shown inFig. 3 looking toward the left, and

Fig. 5, a detail of the clock shown in Figs. 2, 3 and 4, to "be referredto.

It is believed that the invention will be more clearlv and easilycomprehended by first describing in detail the construction of theelectrically driven clock preferred by me and which is shown in Figs. 2to 5 inclusive.

Referring to Figs. 2, 3 and 4, 10 represents a bipolar field magnet foran alternating current motor a, and 12, 13, are opposite poles of saidmagnets, each of which poles is (hvided so as to produce a rotatingfield by means of the shading coils 14, 15, which latter cause themagnetism in the pole faces 16, 17, to lag somewhat behind the magnetismin the pole faces 18, 19. In the space mclosed by the poles 12. 13,wherein the magnetic field revolves, there is a rotor, preferably madeas a disk 20 of hardened steel and without windings or slots, andpreferably of the proportions as will be described.

I have found that with such a rotor, the magnetic remanence produces astrong starting torque and a very marked tendency to run in exactsynchronism, because the magnetic lines through themass of the rotortend strongly to remain fixed, and after synchronism has been reached tocause the rotor to act as if it were polarized. This synchronous motoris arranged with a driving shaft 21 for the rotor 20 verticallyarranged, and with the rotor 20 sufliciently below the middle of thepole faces so as to rise, when in action, and thus take the entireweight ofthe rotor and its shaft off of its bearings, and thus eliminateall end thrust friction.

Upon the shaft 21 is cut a worm thread 23, which engages a worm gear 24,having its shaft 25 provided with a worm 26, which drives a worm gear 27The double reduction just described, provides a reduction in speed fromthat of the rotor 20, revolving for example, 3600 revolutions per minutein the case of a 60 cycle circuit, to 1 revolution per minute on theshaft 28 of the worm gear 27.

The shaft 28 may therefore carry the second hand, not shown, of a clock.

For the purpose of reducing friction and wear and eliminating externalinterference,

the rotor 20 of the motor and the reductiongearing described areinclosed in a nearly air-tight case 29, containing fine lubricating oil,which is distributed by the motion of the shafts and gears over all thesurfaces in contact, thus insuring efiicient lubrication.

From the shaft 28, revolving once per minute, connection is made bysuitable earing 30, 31, 32, (see Fig. 4) to the minute hand gear 33,which latter is provided with a driving pawl or dog .34, which iscapable of driving in one direction a disk 35, which through the usualfriction washer 36 drives the shaft 37 on which the minute hand 38 ofthe clock is mounted. The sleeve 39 on which the hour hand 40 is mountedis driven III the conventional way 'by back gears 41.

In order to provide against accidental failure of the alternatingcurrent supply, provision is made for mechanically driving the clock,and to' this end I mount an auxiliary clock movement 45, (see Fig. 4),which may be either s ring or weight driven, so as to be capable 0driving the disk 35 through a pawl or dog 46, and I also provide meansfor normally rendering the auxiliary clock movement 45 inoperatlve.

This result may be effected by means of a magnetizable member 50 or somesimilar novoltage device, which will permit the auxiliary movement torun when no current is passing through the coil 47 of the motor a, butwhich will be attracted by the magnet- ISm of the motor when the currentis passing through the coil thereof, and will thenstop the auxiliarymovement 45 by interfering with the motion of the escapement 1ever 51 orotherwise. I In the present instance, (see Fig. 3), the magnetizablemember 50 is shown as carried by a lever 52, which has its arm 53adapted to be engaged with the escapement lever 51, when the member isin its attracted position,

thereby stopping the auxiliary movement.

alternating current is on, the clock hands will be electrically drivenat a rate proportionate to the frequency of the current, and if thefrequency is correct, the clock will keep accurate time, while if thecurrent fails the auxiliary movement will instantly begin to drive theclock hands and will continue to do so until the current is restored tothe circuit.

Such a clock provides ideal means for indicating time in all centers ofpopulation where alternating current is distributed, and enablesexisting commercial alternating current systems to provide theindividual users of such current for lighting, power and other purposes,with accurate time, inasmuch as said clocks can be connected in thealternating current systems as now installed, without the necessity ofspecial wiring, as it is only necessary to connect the motor a with thesocket of an incandescent lamp, or with any other socket included in thesystem.

he user of the alternating current for lighting, power or otherpurposes, can thus I be furnished with a clock Wl'llCh requires nowinding or batteries to be renewed and which can be operated at veryslight expense.

Provision must be made however for insuring that the time indicated bythe clocks in the alternate current systemais accurate or substantiallyso, and to this end, means are provided at the central station of thealternating current s stem, for determining that the inte ated aternations are proportional to the e apsed time.

In the present instance, I have shown in Fig; 1, one means foraccomplishin result, which consists of a standard cIock b of any knownor reliable make, and alongside of it foreasy observation, a synchro"nously driven clock 0, which is of the construction above described andillustrated in Figs. 2 to 5. The clock a has its motor a connected bythe wires 60, 61, with the main line circuit of an alternating current sstem, which main line circuit is represented y the wires 62, 63, 64,which are supplied with current by an alternating current generator 65,

thisno represented as a three-phase generatorg is extended outsidethereof and has connected with it electric lamps 68, clocks like theclock a, but which to facilitate description of the operation of themethod of time distribution' are marked d.

The main line circuit is also shown as furnishing current to a motor 70for power or other purpose.

The clocks d may be locatedin the oflices factories, or other placeswhere are locate the individual customers of the company operating thealternating current system.

The standard clock I) may be regulated every day by means of signalsfrom Washington or other center of standard time, and therefore can bedepended upon to indicate the correct time, while the indication of theclock 0 depends upon the integrated alternations.

It is obvious that all the clocks d, which may be designated thesecondary clocks in the system, will always show the same time as thecomparison clock 0, consequently if the speed of the prime mover 66 inthe central station is corrected from time to time, so as to graduallywipe out any excess or deficiency in the sum, of the alternations, whichhas caused the comparison clock to gain or lose slightly with respect tothe standard clock 5, the same action will correct simultaneously allthe secondary clocks c in the system.

lhis adjustment of speed of the prime movers can be accomplished bymeans of speed controllers, which are commonly provided for thegovernors of prime movers, such as large engines or turbines.

In the present instance, I have conventionally represented in Fig. 1, aspeed controller for the engine or prime mover 66, which consists of anelectric motor connected in circuit with the main line wires 62, 63, andwith circuit controllers represented as push buttons 81, 82, which aremarked F and. S to represent fastand slow.

The motor 80 is operatively connected through suitable gearing 83 withthe governor 84 for the prime mover.

As represented in Fig. 1, the push buttons 81 82, are connected with themotor 80 by wires 85, 86, and. with the line wire 62 by wire 87, and themotor 80 is connected with the line wire 63 by the wire 88.

It will thus be seen, that the operator at the central station canoperate the motor 86 to adjust the governor 84 and thereby regulate thespeed of the prime mover 66, by manipulating the push button 81 or 82 tocause the motor 80 to revolve so as to move the governor to increase orreduce the amount of steam supplied to the prime mover, according towhether it is desired to speed up the prime mover or to slow downclocks, for the reason that these temporary variations in speed areequally liable to be positive or negative and thus neutralize eachother, while in all cases they are brief and have little effect upon theintegrated alternations. The ordinary engine or turbine governors aredesigned to automatically take care of these temporary variations inspeed. In a large power station it is unusual, where for example, thenormal frequency is 60 cycles to have this fall below 59 cycles or riseabove 61 cycles, and such a deviation would not usually last more than15 or 20 seconds. Even if the frequency should fall one cycle and remainlow for five minutes the accumulated error in the secondary clocks wouldonly be five seconds. As soon as the station attendant noticed adifference between the second-hand of the comparison clock and thesecond-hand of the standard clock, he would make a slight adjustment of,the speed controller of the turbines, and

within the next ten or fifteen minutes the error would disappear. Suchadjustments of the speed controllers would not need to be inade oftenerthan two or three times an hour, in order to maintain the secondaryclocks always correct within a very few seconds, and this would bescarcely more arduous than the present method of regulating the speed byobserving a frequency indicator, which is a comparatively crude andinaccurate method as compared with the present method.

ln the present instance, I have illustrated one system or arrangement ofapparatus by means of which the difference in time between thecomparison clock and the standard clock is made by the eye of theoperator comparing the two clocks, but it is not desired to limit theinvention in this respect.

lfn the present instance, I have shown and described one embodiment ofthe in- Vention, which has been selected on account of its simplicity toenable the invention to be readily understood, but it is not desired tolimit the invention to the particular systeln herein shown.

By reference again to Figs. 2, 3 and 4t, it

will be observed that a rotary magnetic field is produced by the currentflowing through the motor a, and that this rotary magnetic field has adefinite time value and is magnetically coupled with the hands of theclock to produce rotary movement thereof.

The synchronous motor may and preferably will be provided withan air gapbetween its poles audits rotor, of a width which is at least equal toand preferably greater than the axial thickness of the r0- tor,andexcellent results have been obtained with a motor having a field Whosepolar diameter is ten-sixteenths of an inch, and having its rotor of adiameter of seven-sixaccumulated errors in the integrated alterteenthsof an inch and a thickness of less than one-sixteenth of an inch.

Claims:

1. A system for distributing time indications, consisting of acommercial alternating current system, a standard clock and a comparisonclock driven synchronously with the alternations through suitablegearing to run at the rate of the standard clock when the frequencyis'normal, means to correct nations, secondary clocks driven bysynchronous motors through suitable gearing to indicate the same time asthe comparison clock, and auxiliary means to drive the secondary clocksif the alternating current fails.

2. A system for distributing time, comprising an alternating currentcircuit supplied with an alternating current whose frequency issufliciently high to be used for commercial lighting, a clock having atime element driven by self-starting synchronous motor included in saidcircuit and capable of remaining in exact synchronisin with thealternations of the current'flowing through said circuit, and a standardtime with which said clock may be compared.

3. A system for distributing time, com

prising an alternating current circuit supplied With an alternatingcurrent whoseirequency is sufiiciently high to be used for commerciallighting, a clock having a time element magnetically coupled by aselfstarting rotor inherently capable of revolving in exact synchronismwith a rotating magnetic field maintained by the said current, and meansfor providing for a definite relation between the rotations of saidfield and elasped time.

4. The method of distributing time indications whereby the length oftime that an alternating current is flowing through an electric circuitmay be accurately ascertained irrespective of the number ofinterruptions in the flow of said current, which consists in includingin said circuit a clock driven by a self-starting synchronous motorcapable of running in absolute synchronisni with the alternations ofsaid current and adjusting the frequency of the alternations of saidcurrent for any difference between said clock and means indicatingstandard time.

In testimony whereof, I have signed my name to this specification.

HENRY E. WVARREN.

